Abstract: Apparatus for forming a non-rotating helix of metal strip. The apparatus includes a store for the strip rotatable about the axis of the helix. The store has a radially inwardly facing circumferential opening from which the strip is withdrawn by guide shoes which are also rotatable about the axis of the helix but at a different rotational speed to that of the store so that the difference in diameter of the strip on leaving the store and entering the helix is accommodated. The guide shoes deliver the strip to guide rollers rotating with the guide shoes by which the strip is guided in a spiral to non-rotating helix-forming shoes from which the coils of the helix are delivered in an axial direction.

Abstract: A method of making interlocked metal tube from a strip of the metal of generally S-shaped cross-section by which the shaped strip is formed into a helix without interengaging adjacent coils of the helix, passing the helix without rotation through a rotating driving means to move the non-rotating helix axially, interengaging adjacent coils of the helix and then performing an operation to prevent subsequent disengagement of the adjacent coils, thereby to form an interlocked metal tube. The driving means for the helix is a rotatably-driven mandrel around which the open helix is placed. The mandrel has intermediate its ends a radially-outwardly extending integral portion in which there is a helical passageway forming a tunnel through which the helix is passed and from which the helix is delivered to move without rotation axially along the remainder of the mandrel.